Graphene, a material that consists of a lattice of carbon atoms, one atom thick, is widely touted as being the most electrically conductive material ever studied. However, not all graphene is the same. With so few atoms comprising the entirety of the material, the arrangement of each one has an impact on its overall function.
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Marilyn Minus, a materials expert and assistant professor at Northeastern Univ., is exploring directed self-assembly methods using carbon nanotubes and polymer solutions. So far, she’s used the approach to develop a polymer composite material that is stronger than Kevlar yet much lighter and less expensive. Minus is now expanding this work to incorporate more polymer classes: flame retardant materials and biological molecules.
Rutgers Univ. researchers have developed a technology that could overcome a major cost barrier to make clean-burning hydrogen fuel. The new catalyst is based on carbon nanotubes and may rival cost-prohibitive platinum for reactions that split water into hydrogen and oxygen.
The addition of elements to the surface of graphene can modify the material’s physical and chemical properties, potentially extending the range of possible applications. Recently performed theoretical calculations at RIKEN in Japan show that the addition of oxygen to graphene on copper substrates results in enhanced functionalization. The resulting structure, known as an enolate, make support applications that require catalytic response.
Using graphene ribbons just several atoms across, a group of researchers at the Univ. of Wisconsin-Milwaukee has found a novel way to “tune” the material, causing the extremely efficient conductor of electricity to act as a semiconductor. By imaging the ribbons with scanning-tunneling microscopy, researchers have confirmed how narrow the ribbon width must be. Achieving less than 10 nm in width is a big challenge.
Recent research at the Rice Univ. lab of materials scientist Pulickel Ajayan has discovered that nanotubes that hit a target end first turn into mostly ragged clumps of atoms. But nanotubes that happen to broadside the target unzip into handy ribbons that can be used in composite materials for strength and applications that take advantage of their desirable electrical properties.
Physicists in Europe have solved a mystery that has puzzled scientists for half a century. it has long been known that the distance between the graphene oxide layers depends on the humidity, not the actual amount of water added. But now, with the help of powerful microscopes, it can be seen how distance between graphite oxide layers gradually increases when water molecules are added, and why this phenomenon occurs.
Researchers in Germany have produced a new material the size of a sugar cube that has a surface area equivalent to more than seven tennis courts. This novel type of nanofiber has a highly ordered and porous structure gives it an extraordinarily high surface-to-volume ratio and could be a key enabling technology for lithium-sulfur batteries.
A group of researchers from Russia, Belarus and Spain, including MIPT professor Yury Lozovik, have developed a microscopic force sensor based on carbon nanotubes. The device consists of two nanotubes placed so that their open ends are opposite to each other. Voltage of just 10 nA is then applied to the nanocircuit and force is measured by the change in position of the nanotubes.
At the nanoscale, where objects are measured in billionths of meters and events transpire in trillionths of seconds, things do not always behave as our experiences with the macro world might lead us to expect. Water, for example, seems to flow much faster within carbon nanotubes than classical physics says should be possible. Now imagine trying to capture movies of these almost imperceptibly small nanoscale movements.
An international team has developed an elegant method for producing self-organized and functionalized carbon nanolayers and equipping them chemically with a range of functions. The effort depended on the development of a special compound, the molecules of which were aligned perfectly in parallel to each other in a single self-organized layer, like the bristles on a brush.
The electrons in graphene behave as “massless” particles, yet these electrons also seem to have dual personalities. Phenomena observed in the field of graphene plasmonics suggest that when the electrons move collectively, they must exhibit mass. After two years of effort, researchers at Harvard Univ. have successfully measured the collective mass of “massless” electrons in motion in graphene.
According to researchers, a simple, scalable method of making strong, stretchable graphene oxide fibers that are easily scrolled into yarns and have strengths approaching that of Kevlar is possible. An international collaboration has recently produced graphene oxide yarn fibers much stronger than other carbon fibers.
Scientists are using a pioneering method of “caging” and cooling water molecules to study the change in orientation of the magnetic nuclei at the center of each hydrogen atom in the molecule. This process transforms the molecule from one form of water to another. The results of this work may one day help to enhance the diagnostic power of magnetic resonance imaging scans.
If you don’t want to die of thirst in the desert, be like the beetle. Or have a nanotube cup handy. New research by scientists at Rice Univ. demonstrated that forests of carbon nanotubes can be made to harvest water molecules from arid desert air and store them for future use.
Researchers at the University of California, Riverside Bourns College of Engineering have developed a 3-D, silicon-decorated, cone-shaped carbon-nanotube cluster architecture for lithium ion battery anodes that could enable charging of portable electronics in 10 minutes. It also increases cell capacity and reduces size and weight by 40%.
Short, customized carbon nanotubes have the potential to deliver drugs to pancreatic cancer cells and destroy them from within, according to researchers at Rice Univ. and the Univ. of Texas MD Anderson Cancer Center. Pristine nanotubes produced through a new process developed at Rice can be modified to carry drugs to tumors through gaps in blood-vessel walls that larger particles cannot fit through.
Faster electronic device architectures are in the offing with the unveiling of the world’s first fully 2-D field-effect transistor (FET) by researchers at Lawrence Berkeley National Laboratory. Unlike conventional FETs made from silicon, these 2-D FETs suffer no performance drop-off under high voltages and provide high electron mobility, even when scaled to a monolayer in thickness.
Before 2004, when Geim and Novoselov demonstrated the existence of graphene, a single-atomic-layer-thick crystal of carbon, physicists didn’t believe such a substance could exist. Since then, graphene has attracted tremendous research interest because of its exceptional physical and electrical properties.
Haydale, a U.K.-based developer of a unique plasma functionalization process for nanomaterials, has announced the publication of research showing its functionalized graphene nanoplatelets significantly improve the nanoscale reinforcement of resin. The report states a greater than two times increase in tensile strength and modulus of an epoxy composite using this technology.
Scientists have discovered a material that has the same extraordinary electronic properties as 2-D graphene, but in a sturdy 3-D form that should be much easier to shape into electronic devices such as very fast transistors, sensors and transparent electrodes. The material, cadmium arsenide, is being explored independently by three groups.
Nanotubes have been the subject of intensive research, with potential uses ranging from solar cells to chemical sensors to reinforced composite materials. Most of the research has centered on carbon nanotubes, but other nanotubes’ properties appear to be similar. However, appearances can be deceiving, as researchers have found when examining one variant of nanotube made from boron nitride.
Imperfections in the regular atomic arrangements in crystals determine many of the properties of a material, and their diffusion is behind many microstructural changes in solids. However, imaging non-repeating atomic arrangements is difficult in conventional materials. Now, researchers in Austria have directly imaged the diffusion of a butterfly-shaped atomic defect in graphene.
A team of researchers has successfully tracked single molecules inside living cells with carbon nanotubes. Through this new method, the researchers found that cells stir their interiors using the same motor proteins that serve in muscle contraction. The study, which sheds new light on biological transport mechanisms in cells, appears in Science.
Although the potential uses for graphene seem limitless, there has been no easy way to scale up from microscopic to large-scale applications without introducing defects. Researchers in Chicago and Korea have recently developed a supersonic spray system that produces very small droplets of graphene which disperse evenly, evaporate rapidly, and reduce aggregation tendencies. And, to the researchers’ surprise, it also eliminates defects.
Soon after graphene’s isolation, early research already showed that lithium batteries with graphene in their electrodes had a greater capacity and lifespan than standard designs. At the Univ. of Manchester, U.K., where graphene was first isolated, researchers are working with more than 30 companies to advance technology in graphene-enabled energy storage, particularly in the area of lithium-ion batteries and supercapacitors.
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